In the past decade, there has been enormous development in the area of wireless communication systems. Particularly, wireless local area network (WLAN) technology has emerged as one of the prevailing wireless technologies throughout the world. Also, in the fourth-generation, the WLAN technology may play an important role in the wireless and mobile communication systems.
Typically, WLAN devices may operate in accordance with one or more protocol standards including, but not limited to, IEEE 802.11. Moreover, the protocol standards for the WLAN devices are upgraded based on certain factors, such as the data rate and throughput requirements, in the communication system. For example, the IEEE 802.11 specification has evolved to IEEE 802.11 standard, which later evolved to IEEE 802.11b standard. Further, the 802.11b standard has evolved to IEEE 802.11g standard and then to IEEE 802.11n standard.
In addition, the WLAN devices may include legacy devices, high throughput (HT) devices, and very high throughput (VHT) devices. The legacy devices are compliant to IEEE 802.11abg standards. Also, the legacy devices may provide a maximum data rate of 54 Mbps. On the other hand, the high throughput (HT) devices are compliant to IEEE 802.11n standard. With the development of MIMO-OFDM technology, the HT devices may provide a maximum data rate of 600 Mbps. In a similar manner, the VHT devices are compliant to IEEE 802.11ac standard. Moreover, there has been development in a very high throughput physical layer and a medium access controller (MAC) layer of the VHT devices to support a data rate of more than 1 Gbps.
Typically, a device that is complaint to IEEE 802.11n standard should be backward compatible to the legacy devices supporting a legacy frame format in addition to HT mixed and green-field formats. Similarly, a device that is complaint to IEEE 802.11ac standard should be backward compatible to the legacy devices and HT devices supporting legacy and HT frame formats in addition to its own VHT mixed format. To achieve this compatibility, a device at a receiver end should be capable of detecting the format of the frame for successful decoding of the frame/packet. Thus, proper detection of the frame format is very crucial in the wireless communication systems.
In a conventional system, signal fields in a received frame are employed to detect the frame format. Particularly, the frame format is detected based on decoded bits in the signal fields and phase rotations of the signal fields. However, the decoded bits and phase rotations in the signal fields may be incorrect due to multipath fading and degradation of the frame prior to reaching a receiver. For example, a signal may travel through a wireless multipath channel, and the signal may undergo various forms of degradation before reaching the receiver. This degradation of the signal may cause the decoded bits to go wrong at the receiver, which further causes wrong detection of the frame format.
It is therefore desirable to develop a robust detection technique that is capable of detecting the frame format even under multipath channel and fading conditions.